Associations between Ambient Air Pollution Exposure and Menstrual Cycle Irregularity in Premenopausal Women

This study investigates the associations between various air pollutants and menstrual cycle irregularity.

Data for premenopausal women were obtained from the Korea National Health and Nutrition Examination Survey (n=4478). We evaluated the associations of moving averages of five air pollutants over 90, 120, 150, 180, and 365 days with short-interval (menstruation occurring at least once every 3 months) and long-interval (menstruation skipped for ≥ 3 months) menstrual cycle irregularity using multinomial logistic regression models. The joint effects of air pollution mixtures were explored using the quantile g-computation method.

Interquartile range increases in moving averages of nitrogen dioxide (NO₂) and sulfur dioxide (SO₂) over 90, 120, 150, and 180 days were associated with short-interval menstrual cycle irregularity [e.g., odds ratio (OR)=1.24, 95% confidence interval (CI): 1.03, 1.50 for NO₂ over 120 days; OR=1.07, 95% CI: 1.03, 1.12 for SO₂ over 150 days]. Each quintile increase in air pollution mixture (NO₂ over 120 days and SO₂ over 150 days) was also associated with short-interval menstrual cycle irregularity (OR=1.07, 95% CI: 1.00, 1.14).

Our results indicate associations between various exposure indices of NO₂ and SO₂ and short-interval menstrual cycle irregularity in a representative sample of Korean premenopausal women. This research represents one of the first investigations on this issue; therefore, further longitudinal studies are warranted to confirm these findings.